ANDREW COLLETT Concepts in Mainframe Computing. Contents Brief History and General Information...
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Transcript of ANDREW COLLETT Concepts in Mainframe Computing. Contents Brief History and General Information...
ANDREW COLLETT
Concepts in Mainframe Computing
Contents
Brief History and General Information
Pros/Cons of Mainframes
Terminology
Concepts used in the mainframe world
Mainframe process example
History & General Information
IBM Mainframe Definition ..”a large computer, in particular one to which other
computers can be connected so they can share facilities the mainframe provides.... The term usually refers to hardware only, namely, main storage, execution circuitry and peripheral units”
MIPS Million instructions per second IBM’s way of rating their mainframes
History & General Information
First IBM Mainframe April 7, 1964 - System/360 $5.5 Million to purchase or
~$3,000-$100,000/month rental 0.0018 to 0.034 MIPS
IBM zEnterprise System – 2010 5.2Ghz per core with up to 96 cores on a single
machine 3 TB of main memory 78,426 MIPS industry standard today – more variations ~$33 Million to buy/install and ~$256,000 / year to
maintain
Pros of Mainframes
Extremely fast
Can handle a huge workload 24/7
Consolidates the entire system together
Easy to manipulate data quickly
Great for transaction processing
Ton of support through IBM
Cons of Mainframes
Very expensive up front cost
Expensive to maintain – MIPS and hardware maintenance
Have to pay based on how many MIPS are actually being executed - if renting
Complex system – high learning curve
Not good for number crunching or doing complex calculations
Some systems can be old and outdated
Why are mainframes still around?
Nothing can match the speed of data processing that mainframes deliver
Nothing can match the volume and reliability of data processed
Has a lot of money, time, and energy invested into it Esp. IBM – TON of support Older systems cost too much to replace
Old systems need maintenance Trillions of lines of code that is used everyday Banks, financial institutions, big businesses, etc
Terminology
EBCDIC EBCDIC is a standard similar in concept to, but not
compatible with, ASCIICOBOL
A business-oriented programming languagez/OS
A 64-bit operating system that allows for virtualization of resources – what mainframes newer than 2000 run on
REXX A scripting language that is similar in concept to Perl
and Python
Terminology
CICS A transaction server for online and batch processing
JCL A scripting language for executing batch programs
Batch Schedule based jobs that runs every night with an
interconnected series of scriptsDB2
the IBM relational database management system, also available on other platforms
EBCDIC
Extended Binary Coded Decimal Interchange Code
Devised in 1963-1964 by IBM to co-release with its System/360 mainframe
8-bit character encoding Developed separately from the 7-bit ASCII encoding
scheme
EBCDIC
COBOL
COmmon Business-Oriented Language
Used in mainframes because they were built and structured around each other
Business oriented language so it is English like
Easy to read in files and manipulate records while applying business logic
REXX
Restructured Extended Executor
Developed by IBM
Designed as a macro or scripting-like language so each mainframe system can do unique things
Allow for developers to make ‘App-like’ programs on the mainframe. Ex. Typing a shortcut on the command line Small program to cleanup some files
REXX
REXX
z/OS
64-bit operating system that runs on mainframes designed by IBM Needs to be at least a “zSeries” or newer mainframe
Record-oriented data access methods
Supports Java, C++, and C# (built in compiler)
Comes with all the necessary tools to work on a mainframe – CICS, DB2, JCL, REXX, etc.
z/OS
Meant for continuous, high-volume operation with high security and stability
Newest version – IBM Rational Development for System Z z/OS on Windows No ‘Green Screen’ Nice GUI – based on Eclipse client Has subversion type software built in Has ‘Content Assist’ – just like Intellisence
IBM Rational Development for System Z
CICS
Customer Information Control System
Is a Teleprocessing monitor server a control program that monitors the transfer of data between
multiple local and remote terminals to ensure that the transaction processes completely or, if an error occurs, to take appropriate actions
Transaction server that runs mostly on IBM mainframe systems under z/OS
Middleware designed to support high-volume online transaction processing
CICS
CICS transaction is a unit of processing initiated by a single request that may affect one or more objects
Interacts with resources such as files, database connections, terminals, or to invoke functions such as web services
Manages the entire transaction – if transaction fails all recoverable changes can be backed out
90% of Fortune 500 companies run on CICS Bank teller systems, ATMs, insurance agencies, record keeping,
etc.
JCL
Job Control Language
Instruct the system on how/when to start a batch job
Job, steps, and procedures
JCL has scripting-like tools that can be used depending on the system Sort files before running, copy data to a different
location, etc
JCL Example
JCL
Once the JCL is made without syntax errors it can be ‘submitted’ to the mainframe
The mainframe will run the job just as the card says
The example shown will run the program named ‘COBPROG’ with the given input and output files in addition to the ‘MYINPUT’ input
Batch Processing
Jobs that run directly on the mainframe that do a lot of transaction processing need to be scheduled
No manual intervention – controlled automatically
ProgA needs to run before ProgB because ProgB has input that is created by ProgA
Most companies have their own software on their mainframe that will do job scheduling Zeke for z/OS Event Scheduling
Zeke
DB2 for z/OS
Database server product developed by IBM – DBMS manages incoming data, organizes it, and provides ways for
the data to be modified or extracted by users or other programs
Supports SQL and XQuery
Primary way of getting and storing usable data for programs that need it
Integrated into Rational Development for System Z where it can generate usable error free SQL
DB2
DB2 Error Processing
3 Types of return codes
0 – successful execution
Positive number – successful execution with one or more warnings
Negative number – unsuccessful with an error
Easy to handle errors
Conclusion
All of these concepts work together
Huge sandbox with many tools
Mainframe advancements will continue to be made through these tools along with new mainframe hardware
These are the things that a developer must know in order to be a successful programmer on a mainframe
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
PC
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Rational Development for System Z(z/OS)
PC
Rational Development for System Z(z/OS)
COBOL Program P1
JCL to run the program
Uses DB2Output - Report
PC
Rational Development for System Z(z/OS)
COBOL Program P2
JCL to run the program
Input file is Prog1’sOutput report
PC
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Rational Development for System Z(z/OS)
Batch Scheduler(Zeke)
Set Prog2 to rundirectly AFTERProg1 finishes
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
COBOL Program P1
JCL to run the program
Uses DB2Output - Report
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
COBOL Program P1
JCL to run the program
Uses DB2Output - Report
Gets needed dataVia DB2
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
COBOL Program P1
JCL to run the program
Uses DB2Output - Report
Output
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
Output
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
COBOL Program P2
JCL to run the program
Input file is Prog1’sOutput report
Output
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
COBOL Program P2
JCL to run the program
Input file is Prog1’sOutput report
Input
ZEnterprise Mainframe
z/OS
CICSDB2JCLREXXCOBOLBATCHEBCDICJAVAC++C#
Nightly Batch Processing
P2 finished
References
"ASG-Zeke." ASG Software Solutions. 10, July 2013. Web. 14 Oct. 2013. <http://www.asg.com/Products/View/ASG-Zeke.aspx>.
"CICS." CICS LU6.2 User Data. Microsoft, 2013. Web. <http://msdn.microsoft.com/en-us/library/gg166110.aspx>.
Grega, Al. "A Brief History of the Mainframe World." IBM Destination Z -. Destination Z, 20 June 2012. Web. 15 Oct. 2013.
Hansen, Kris D. "Z/OS Concepts for Java Developers." Z/OS Concepts for Java Developers. IBM, 03 Oct. 2006. Web. 17 Oct. 2013.
"IBM DB2 Database Software." IBM DB2 Database Software. IBM, 1 Oct. 2013. Web. 20 Oct. 2013. <http://www01.ibm.com/software/data/db2/>.
"IBM ZEnterprise System." IBM System Z. IBM, Mar. 2012. Web. 18 Oct. 2013. <http://www-03.ibm.com/systems/z/hardware/zenterprise/>.